Method of and apparatus for indicating the attitude of aircraft



J. N. REYNOLDS METHOD OF AND APPARATUS FOR INDICATING THE ATTITUDE 0FAIRCRAFT Griginal Filed Dec. 30 1918 3 Sheets-Sheet l Wines 86 Aug 12,1924. T 1,504,785

' J. N. REYNOLDS METHOD OF AND APPARATUS FOR INDICATING THE ATTITUDE OFAIRCRAFT Original Filed Dec. 30 1918 3 Sheets-Sheet 2 z 9 z 1 4 w AGHHEEw W I I I IIIIIIIIIIII J. N. REYNOLDS METHOD OFAND APPARATUS FORINDICATING THE ATTITUDE OF AIRCRAFT Original Filed Deg. 5O 1918 3 sheetssheet 3 Inven for v /ifari e 8 Patented Aug. 12, 1924.

UNITED STATES PATENT OFFICE.

JOHN NEwnnnRY nnYNoLns, or GnnnNw IcH, CONNECTICUT.

METHOD OF AND APPARATUS FOR INDICATING THE ATTITUDE OF AIRCRAFT.

Application filed December 30, 1918, Serial No. 268,871. Renewed January21, 1924.

To all wlzom it may concern:

Be it known that I, JOHN NEWBERRY REYNOLDS, a citizen of the UnitedStates, residing in the town of Greenwich, county of Fairfield, andState of Connecticut, have invented a certain new and useful Method ofand Apparatus for Indicating the Attitude of Aircraft, of which thefollowing is a specification.

My invention relates to measuring instruments and more particularly todevices for use in connection with flying machines of theheavier-than-air type in which the weight of the apparatus and its cargois sustained in the air by the reactions result ing .whenthe aerofoilsare moved through the air. The movement of' the aerofoils through theair causes reactions thereon resulting in positive pressure on thebottom camber and negative pressure or suction on the topcamber.

-Positive pressure is caused by the piling up, as it were, of the airbeneath the lower surface of the aerofoil, and negative pressure being ararefaction of the air or a partial vacuum over the upper surface.

It. is the resultant upward components of these reactions which givebuoyancy to the aeroplane, cause it to' be supported above the surfaceof the earth and determines its attitude to the airstream through whichit that the aviator shall be advised as to the sustaining force actingon the aerofoilsand that such sustaining force does. not'drop below acertain minimum value known as the stalling point, that is the value atwhich the apparatus will not be sustained in the air.

shall know the angle .of incidence at which his machine is flying inorder "that'he 'may It is also highly desirable that the aviator operatethe machine most intelligently and efliciently.

One object of my invention is to provide means for indicating the angleof incidence as well as for indicating the buoyancy of the machine atall times during flight.

A further object is to provide means whereby the positive and negativepressures may be taken from difi'erent points on the bottom and topcambers in order to obtain more nearly average pressures over a givenarea, and whereby such average pressures may be conducted to a commonreceiyer.

A further "object is to provide means whereby the indicator may besituated at a distance from the aerofoil and within convenient reach ofthe aviator.

A further object is to provide means for indicating the buoyancy and theangle of incidence on a single instrument.

Further objects are to preventthe entrance of water to thepressureresponsive means, to eliminate vibrations of the device,

and to so construct and arrange the instrumentalities for indicating theangle of incidence that the air inlets will be always presented to thewind.

These and further objects will more fully appear in the followingspecification and accompanying drawings considered together orseparately. 1

I have illustrated one embodiment of my invention in the accompanyingdrawings, in

,which like parts'in all of the several figures 'are designated bysimilar reference characters, and inwhich-- -Fig. 1 is a side elevationof a portion of a biplane embodying my invention.

' 'Fig. 2 is an enlarged sectional view of ortion of an aerofoil.

ig. 3, is a section on the line 3-3 of Fig. 2..

Fig. 4 is a sectional View of an aerofoil showing the pressureresponsiveelements located in the aerofoil and a plurality ofindicators.

Fig. 5 is a front elevation of a modified form of indicator. Fig. 6 is asectional view of the same. Fig. 7 is a detail sectional view of thepressure receiving elements of the angle indicator, the section beingtaken on the line 77 of Fig. 8.

Fig. 8 is a plan view of the same. Fig. 9 is a diagrammatic view of adevlce for making a permanent record of changes in buoyancy and angle ofincidence.

Fig. 10 is an enlarged sectional view of 'the preferred form ofindicator, the section being taken'on the line 1010 of Fi 11.

Fig. his a sectional view of t e same taken on the line 111'1 of Fig.10.

Fig. 12 is an elevation of a portion of the same.

Fig. 13 is a front elevation of a modified form of indicator for use inindicating the. pressure of an enclosed medium.

Fig. 14 is a section on the line 14-44 ofother compartment is likewisedivided into two chambers 6 and 7 by a similar diaphragm 8. The chambers3 and Gare in communication with the atmos here at the top camber of anaerofoil and t e chambers 4 and 7 are in communication with theatmosphere at the bottom camber of the same aerofoil.

Within each chamber 3 and 6 is axially pivoted a flat plate 9 sofashioned that its longitudinal edges will form a helix, and atransverse section, of which at an. point will form a rectangularfigure. A ever 10 pivoted in the chamber 3 1s provided at its free endwith an elongated slot 11 within which the helix engages. The slot is soproportioned and arranged relatively to the helix 9 that any movement ofthe lever on its pivot will rotate thehelix. A pitman 12 is pivotallyconnected to the lever 10 and to the diaphragm 5 whereby movements ofthe latter will be communicated to the lever and thence to the helix.

Carried by the helix 9 is an arm 13 the free extremity of which forms apointer'14 which cooperates with a graduated-scale 15 visible through awindow 16 in the side of the casing 1. Carried by and movable with thearm 13 is a graduated scale .17 for a purpose to be described.

Within. the chamber 6 are carried helix 18 .a lever 19, a pitman 20 andan arm-21 carrying a pointer 22 all operating in the' .same manner asthe corresponding parts ointer 22 cooperates the chamber 3. [The withthe scale 17 carried by the arm 13. j

cylindrical casings 27 and 28.

A sprin 23 is attached to each diaphraghm at the si e opposite theconnection to t e lever 10 or 19 as the case may be. The opposite end ofeach spring is secured to a tensioning screw 24 carried by an arm 24 ona su plemental frame in the chamber at that si e of the diaphragm.

In thedrawings show several different arrangements by means of whichtheindicating means are located in such positions as to be readilyobserved by the aviator.

. In Fi 1, 2 and 3 the pressure responsive and indicating devices are ina single casing as described above. The casing is carried on thefuselage in proximity to the aviators seat and is in communication withthe atmosphere at .the top and bottom cambers of an aerofoil. The deviceis illustrated in connection with one aerofoil of a biplane but Idesireto-have it understood that the invention may be utilized inconnection with machines having any number of sustaining planes and theinstrument may be in communication with, the air on the cambers of anyone or more of such planes or it mayrespond to positive pressures on0111c plane and negative pressures on another p ane.

In Fig. 1 the casing is shown as carried on the framework by means ofwhich the aerofoils are s u ported and over the frontend of the cocEpitin which the aviator is seated. The casing is preferably suspended andpositioned by means of springs 25 in order that it will not beinfluenced by vibrations of the machine.

In the aerofoil 26 and between the top and bottom cambers of the sameare carried two The casing 27 is provided with a plurality of tubes 29each of which communicates with the atmo'sphere at or near the uppersurface of the wing but at different points longitudinally of themachine. The casing 28 has a similar number of tubes 30 in communicationwith the atmosphere at or near the lower surwace of the aerofoil and atpoints directly oppositethe outlets of the tubes 29. The casin 27 is incommunication with the cham er 3 by means of a conduit 31 and the casing28 is similarly connected to the chamber 4 by a conduit 31. By thisarran ement. the pressures in the chambers wil be the'same as that intheir respective casings and the pressures in the latter will beapproximatel the aver e of the pressures at the en s of the tu cs 29 and30 respectively. A portion at least of each conduit is flexible to allowfor relative movements of the casing 1. a

i In order to prevent the admission of water "to the mixing chambers 27and 28 and to the the upper surface and bent over to bring the open endsof the tubes into close proximity to the surface of the aerofoil.Instead of the water seal shown, anysuitable water trap may be utilized.

The chambers 6 and 7 of the casing 1 communicate respectively with theatmosphere at top and bottom surfaces of the aerofoil at ,or near thetrailing edge thereof by 10 means of flexible tubes 32 and 33. The tubescommunicate with wind scoops 34 and 35 respectively. The wind scoops areso proportioned that the entrances thereof lie close to the top andbottom surfaces of the aerofoil and preferably extend over a considerable portion of the surface. This is accomplished by flaring the frontportions of the scoops laterally.- The inlet openings though being longare narrow in order that the area of each opening will be approximatelythe same as that of the bore of the tube. v

The scoops are carried on a vertical pivot 36 carried by the plane andhave attached thereto a vane 37 by means of which the 26 scoops. arealways in position with their orifices presented directly to the wind.In the drawings the scoops are illustrated as pivoted in that framemember of the aerofoil 2 which when in position, is atthe 0 rear ortrailing edge of the aerofoil. The scoops project forward. from thepivots 3 and the scoop entrance is located a short distance forward ofthe trailing edge. Obviously the pivot 36 may be'supported to 85 therear of the aerofoil and the scoop invention in which the pressureresponsive.

4 and indicatin velements are separated, the former being located in theaerofoil and the latter at a distant point. The diaphragm 5 is carriedin a casing 38 which may be directly connected to the tubes 29 and 30.

4 Mechanical connections such as a rack and pinion 39 and a flexibleshaft 40.gear the diaphragm to an indicator 41. The pressures near thetrailing edge will be takenvin a casing 38* and noted on an indicator42.

If desired a single indicating instrument such as illustratedin Figs. 5and 6 may be employed Two pointers 43 and 44 are employed. These aremounted as are the hands of a clock. The hand 43 cooperates 5 with ascale 45 in the casing and the hand 44 cooperates with a scale 46carried by the hand 43. The hand 43 willindicate on'the scale 45 thebuoyancy of -the machine and the relative positionsof the hands asindicated on the scale 46 will give the an le of incidence at which themachine is The hands 43 and 44 may be drivenflexible shafts shown-inFig: -4. In the drawings I have illustrated my in? GI vention inposition to indicate the pressures ying. y the entrance be located asnear to the trailing edge on the upper aerofoil of a biplane and'haveshown the openings through which the pressures are transmitted to thepressure responsive mechanism as arranged in hne wlth the longitudinalcenter of the machine, and

out of the influence of currents set up by the points on the machine andall communicate with a single indicator so that the average pressures beobtained. I prefer to arrange the inlets of the tubes 29 and 30 onebehind the other as shown and also slightly out of line as viewed fromabove whereby the forward openings will not interfere with those to therear. -The inlets of the tubes 32 and 33 as near the trailin edge of thesupporting surface as possib e, as according tom present knowledge, theyfunction most of fectively when so located.

By means of the manifolds 27 and 28 or of connecting the inlet tubes inmultiple with their respective chambers in the pressure responsiveelement as shown in Fig. 4 ap: proximately average pressure'saresecured. Working with such low pressures and with such slightvariationbetween pressure and suction this feature is of rimeimportance.

While I have shown t e inlet tubes on opposite sides of the aerofoil assimilar in number for each indicator and as communicating with theatmosphere directly oppo-.

tubes maybe located as desired and the numher in one camber may differfrom that in the other.

In Fig. 9 I show an arrangement by means of which a permanent record ofchanges in buoyancy and angle may be made. The diaphragm 5 may carry amarker 47 cooperating with a movin tape 48 for recording the buoyancy.The iaphragm 7 is provided with a marker 49 engaging a tape 50 forrecording changes in the angle of incidence.

The operation is as follows:

When the machine is at rest the air pressure is the same on both eambersof the aerofoil and the diaphra s 5' and 8 will assume the neutralpositions. As the machine is set in motion, as by the propeller, the airpre$ure on the sides of the diaphragms open to the bottom camber willincrease and the pressure on theopposite side will decrease. diaphragmstoward the regions of lower pressure, and by properly calibrating theThis will cause a movement of the f stream, the operator will swing thetail flap or elevator upward. This will cause the leading edges of theaerofoils to be tilted upward and change the angle of incidence and thechange in pressures on the cambers will flex the diaphragms and causethe pointer 14 to indicate the buoyanc of the machine on the scale 15and at t e same time the pointer 22 will indicate the new angle ofincidence on the-scale 17.

Both diaphragms 5 and 8 with their associated pointers 14 and 22, willbe displaced an equal amount by a change in buoyancy due to a change inair speed. They will be displaced an unequal amount by a change due toan alteration of the an 1e of incidence, i. e. with the anglehe (1constant and the air speed changed the two diaphragms and associatedpointers will respon alike to the altered pressures resulting. Ifhowever, the an le is also changed the two diaphragms wil not respond inunison, one being moved to a greater or less de ee than the other.

t will be found that this relative movement between the two diaphragmswill be a different amount for each angle of incidence and that it willbe the same at any parttiicular angle within the range of flying spee s.j

Assuming that with the plane in flight and at a constant angle ofincidence, the buoyancy will be read by the position of pointer 14 onthe scale 15. The angle will be read by the position of the pointer 22relative.

to the scale 17 If now the air speed be increased both pointers 14 and22 .will advance an equal amount with respect to the scale 15 but if theangle be permitted to change, the amount of the change and the new angleresulting will be shown by a different position of the pointer 22relative to scale 17.

If the speed of the machine changes due to variations of engine speed orchanges in wind pressure, the pointers will move relatively to the scale15 and theoperator can tell at a glance that either the air speed or theangle has changed and can so manipulate the machine to make the, desiredcorrections.

It is obvious-that while areading of the sum. of the positive andnegative pressures is desirable, a readin of either may be suflicient.If itv be de'sira Is to make note of the positive pressure only thetubes communicating with the atmosphere at the top camthe interior maythe suction is to be-relied upon no communication with the bottom camberwill be necessary. The buoyancy may be indicated of a sheet of t in,tough, flexib e material,

both sides of which are coated with a film of a material impervious togas and moisture. A thin, tough paper, such as is used in Japan insteadof glass 1n windows, and for covering unbrellas, coated on both sideswith artists varnish applied by sprayin is admirably adapted for thisurpose. is varnish, while it dries to sue an extent as to lose its tackynature, does not become rigid, will not crack under the usual extremesof temperature, but remains pliable under all ordinar conditions.

In Figs. 13 an 14 I have illustrated an embodiment of my invention,particularly adapted for measuring the pressure of inclosed gases, such,for example, as in aerial devices of the lighter-:than-air type,'such asdirigibles, balloons, ballonets, and balloon kites, whereby the properpressure may be applied when filling the envelo and also that theaviator may be advise as to the plrelslsure in the device at all timesduring The embodiment of the invention illustrated comprises a casing 51divided into two chambers 52 and 53 by means of a varnished paperdiaphragm 5. One side 54 of the casing ma be of ass, in order that eviewe l. The diaphragm is supported between two rings 55 and 56 whichare retained in position by means of an annular nut 57, which engagesthe interior of the casing, and the ringsv carrying the diaphragm areheld against an annular shoulder in'thecasing by meansgf the nut 57. Agasket 57 is interposed between the ring and shoulder, thereby produc" agastight joint between the chambers. l he said gasket is in the form ofa cylindrical rin resting in groovesin the ring 55 and shoul der.Thering 55 is provided with a circular recess 58 on one face thereof,and the ring 56 has circular beads 59 on one face. When the rings are inposition the bead 59 will enter the recess 58 and securely retain thedia hragm in position.

he ring 55 carries a yoke 60 and a spring 61 is attached to the yokearid to the diaphragm The tension of the spring may be adjusted, asshown in Fig. 10, or otherwise, or the tensioning feature may be ber maybe omitted. If, on the other handomitted if desired.

The ring 56 carries a yoke 62, and extension 63, and a bracket 64. Theyoke 62 carries a conical pivot point '65, and the ex- 68 pivoted to thebracket 64, and the said lever is connected to the diaphragm by means ofa pitman 69 which is connected to the center of the diaphragm. A setscrew 62 carried by the yoke 61 is adapted to be engaged by thelever 68and limit the movement of the diaphragm toward the spring 61. A screw 68passes through the slotted end of the lever 68 whereby the slot 68 maybeadjusted. The helix 67 carries at one end a hand or pointer 70, whichco-operates with a scale 71 carried by the bracket64, and the pointerand scale are visiblethrough the front 54 of the casing.

. The chamber 52 is in communication with the interior of theelementcontaining the gaseous flllHl by means of a fiexlble tube 72,

i and the chamber 53 is in communication with the atmosphere by means ofa breathing opening 7 The yoke. or bridge member, 62, is so positionedrelatively to the diaphragm that the latter. or some attachment. carriedthereby, will contact with the yoke and limit the moven'ient of thediaphragm in that direction. Under normal conditions the diaphragm.owing to the slight pressures to be measured. will not be moved to anextent sutlicient to contact with the yoke. The yoke 62 may be adjustedtoward-or away from the initial tension.

diaphragm,-or the yoke may carry an adjustable device with which thediaphragm may contact.

The spring 61 will prevent excessive movement of the diaphragm in theopposite direction. but other limiting means may, if desired, beemployed.

' The diaphragm 5 is inert and is not under It will not assume thecentral position except when moved by pressure in the chamber 52. Itsnormal position is that shown in dottedlines in Fig. 14.

In accordance with the provisions of the patent statutes, I havedescribed the 'prin ciple of my invention, together with the apparatuswhich I now consider to represent the best embodiment thereof; but Idesire to have understood that the apparatus shown is merelyillustrative and that the invention maly be. carried out in other ways.

aving now described my invention what I claim and desire to secure byLetters Patent is:

1. Anindicator for flying machines, comprising an aerofoil, meansresponsive to air reactions due to that relative movement of the air andaerofoil which produces the necessary lifting forces, there being aconduit communicating with the responsive means and the air, saidconduit having an opening in proximity to and facing-the top surface ofthe aerofoil.

2. An indicator for flying machines, comprising an aerofoil, a diaphragmresponsive to air reactions above and below the aerofoil due to therelative movement of the air and aerofoil which produces the necessarylifting forces. there being a tube communicating with one side of thediaphragm and with the atmosphere above the aerofoil, said tubeextending above the aerofoil, there being a return bend in the tube, theopen end of the tube being in proximity to the topcamber of theaerofoil, there being a tube communicating with the other side of thedia surface ofthe aerofoih'there beinga passage communicating with theopposite side of the diaphragm and with a plurality of points at thelower surface of the aerofoil, whereby the diaphragm will be responsiveto air ractions above and below the aerofoil due to that relativemovement of the air and acrofoil which produces the necessar liftingforces, a scale located at a point removed from the diaphragm, a pointercooperating-with said scale, and means whereby the pointer may be movedby movements of the diaphragm.

4. An indicator for flying machines,jcomprising an aerofoil, there beinga series of openings in a surface of the aerofoil, said opening beinglocated at different distances from the leading edge of the aerofoil,there being a chamber in communication with said openings, and meansresponsive to variations in pressure at said openings.

5. An indicator for flying machines, comprising an 'aerofoil, therebeing a series of openings in a surface of the acrotoil, said openingsbeing located at different. distances from the leading edge of the.aerofoil, there being a chamber in communication with said openingsmeans responsive to variations in pressure at said openings, and meansfor. indicating movementsof the re. sponsive means. '7

6. An indicator for flying machines, comprising an aerofoil, there beinga series of openings in a surface of the aerofoil, said openings'beinglocated at diilerent distances from the leading edge of the aerofoil,there being a chamber in communication with said openings, and meansresponsiveto variations in pressure at said openings, said pressureresponsive means being located at a distance from the aerofoil. 7. Anindicator for flying machines,- com prising an aerofoil, there being aseries of openings in a surface of the aerofoll,

said openings being located at different distances from the leading edgeof the aerofoil, there being a chamber in communicaatmosphere at thebottom surface of the sponsive and indicating means being located at adistancefrom the aerofoil.

9. An indicator for flying machines, comprising an aerofoil, there beinga series of openings communicating with the atmospiere at the uppersurface of the aerofoil, said openings being located at differentdistances from the leading edge of the aerofoil, said openingscommunicating with a common chamber, a similarly disposed series ofopenings communicating with the atmos- .-phere at the bottom surface ofthe aerofoil, said openings leading to a common chamber, and meanscommon to all of said openings flDd IBSPOIISIVG to air reactions due tothat relative movement of the air and aerofoil which produces thenecessary lifting forces at any or all of said openings.

'10. An indicator for flying machines, comprising an aerofoil, therebeing a series of o enin'gs communicating with the atmosphere at theuper surface of the aerofoil, said openings e-ing located at differentdistances from the leading edge of the aerofoil, said openingscommunicating with a common chamber, a similarly disposed series ofopenings communicating with the aerofoil, said openings leading to acommon chamber, means common to all of said openings and responsive toan reactions due to that relative movement of the air and aerofoil whichproduces the necessary lifting forces at any or all of said openings,and means for indicating the value of, the lifting vforces.

11. An indicator. for flying machines,

comprising an aerofoil, there'being a series of o enings communicatlngwith the atmosp ere at'the uppersurface of the aerobeing located atdiffoil, said openin v om the leading edge of ferent distances 7 theaerofoil, said openings communicating with a common chamber, asimiliarly disposed series of openings communicating with the atmosphereat the bottom surface of the aerofoil, said openings leading to a commonchamber, and means common to all of said openings and responsive to airreactions due to that relative movement of the air and aerofoil whichproduces the necessary lifting forces at any or all of said openings,said responsive means being lfociated at a point distant from the aero-12. An indicator for flying machines, comprising an aerofoil, therebeing a series of openings communicating with the atmosphere at theupper surface of the aerofoil, said openings being located at differentdistances from the leadlng edge of the aerofoil, said openingscommunicating with a common chamber, a similarly disposed series ofopenings communicating with the atmosphere at the bottom surface of theaerofoil, said openings leading to a common chamber, means common to allof said openings and responsive to air reactions due to that relativemovement'of the air and aerofoil which produces the necessary liftingforces at any or all of said openings, and means for indicating thevalue of the lifting forces, said responsive and indicating means beinglocated at a distance from the aerofoil.

13. An aeroplane comprising an aerofoil, and means responsive to airreactions on the aerofoil due to chan es in the angle of incidence ofthe aerofoil.

14. An aeroplane comprising an aerofoil,

means responsive to air reactions on said aerofoil due to that relativemovement of the air and aerofoil'which produces the necessary liftingforce for indlcating the buoyancy of the aeroplane, and means responsiveto air reactions on the aerofoil for indicating the angle of incidenceof the aerofoil. 15. An aeroplane comprising an aerofoil. and meansresponsive to air reactions above and below the aerofoil due to changesin the angle of incidence of the aerofoil.

16. An aeroplane comprising an aerofoil, means responsive to airreactions above and below said aerofoil due to that relative movement ofthe air and aerofoil which produces the necessary lifting force forindicating the buoyancy of the aeroplane, and

means responslve to air reactions above and below the aerofoil forindicating the angle of incidence of the aerofoil.

' 17. An aero lane comprising an aerofoil, means carried y the aerofoiland communicating with the atmosphere in proximity to eating with theatmosphere in proximity to the top and bottom cambers thereof. and

means responsive to air reactions on the.-

aerofoil in proximit to said scoo s for indieating the angle 0 incidenceo the aerofoil.

. of the aerofoil.

20. An aeroplane comprising an aerofoil, pivoted scoops carried by the'aerofoil and communicating with the atmosphere in proximity tothe topand bottom cambers thereof, means responsive to air reactions on theaerofoil in proximity to said scoops for indicating the angle ofincidence of the aerofoil, and means for presenting the mouths of .thescoops to the wind.

21. An aeroplane comprising an aerofoil, pivoted scoops carried by theaerofoil and communicating with the atmosphere inproximity to the topand bottom cambers thereof, means responsive to air reactions on theaerofoil in proximity to said scoops changes in the angle of incidenceof the aerofoil.

23. An aeroplane comprising an aerofoil, and means in communication withthe atmosphere in proximity to the trailing edge of the aerofoil, saidmeans being responsive to air reactions above and below the aerot'oildue to changes in the angle of incidence of the aerofoil.

2%. An aeroplane comprising an aerofoil, means responsive to airreactions on the aerofoil for indicating the buoyancy of aeroplane, andmeans in communication with the atmosphere in proximity to the trailingedge of the aerofoil, said means being responsive to air reactions onthe aerofoil due to changes in the angle'of incidence of the aerofoil.

25. An aeroplane comprising an aerofoil,

4 means responsive to air reactions on .the

aerofoil for indicating the buoyancy of aeroplane, and means incommunication with the atmosphere in proximity to the trailing edge ofthe aerofoil, said means being responsive to air reactions above andbelow the aerofoil due to chan es in the angle of incidence of theaerofoi A 26. An aeroplane comprising an aerofoil,

a scoop having an inlet opening therein and. in communication with theatmosphere in proximity to the surface of the aerofoil,

said inlet opening being in proximity to the trailing edge of theaerofoil, and means responsive to air reactions on the aerofoil forindicating the angle of incidence of the aerofoil.

27. An eeroplane comprising an aerofoil,

scoops eac 1 having an inlet opening therein and in communication withthe atmosphere in proximity to the top and bottom cambers of theaerofoil, said inlet openings being -in proximity to the trailing edgeof the aerofoil, and means in communication with said scoops andresponsive to air reactions on the aerofoil for indicating the angle ofincidence.

28. An aeroplane. comprising an aerofoil, pivoted scoops each having aninlet opening therein and in communication with the atmosphere inproximity to the top and bottom cambers of the aerofoil, said inletopenings being in proximity to the trailing edge of the aerofoil, meansin communication with said scoops and responsive to air reactions on theaerofoil for indicating the angle of incidence, and means for presentingthe mouths of the scoops to the wind.

29. An aeroplane compimmz an aerofoil and means responsive to airreactions on the aerofoil for indicating the buoyancy and angle ofincidence of the aerofoil.

30. An aeroplane comprising an aerofoil and a single instrumentresponsive to air reactions on the aerofoil for indicating the buoyancyand angle of incidence of the aerofoil.

31. An indicator for flying machines, comprising an aerofoil, a casing,a flexible diaphragm within the casing and dividin the same into twochambers, one of sai chambers being open to the atmosphere at the top ofthe aerofoil, the other of said chambers being open to the atmosphere atthe bottom'of said aerofoil, a levenpivoted within the casing,connections between said lever and the diaphragm whereby the lever willbe moved in response to movements of.

said diaphragm, a rotatable helix within the casing, a pointer carriedby the helix, connections between the lever and helix whereby movementof the lever longitudinally of the helix will rotate the latter and movethe pointer, and a scale cooperating with the pointer.

32. An indicator for flying machines, comprising an aerofoil, a-ca-sing,means within the casing, and responsive to air reactions above and belowthe aerofoil due to that relative movement of the air and aerofoil whichproduces the necessary lifting forces, for indicating the buoyancy ofthe machine, and means within the casing, and responsive to airreactions. above and below the I comprisin a casing,

' partment dividing the same Into two cham- I sobers one of which is incommunication with the atmosphere above the aerofoil and the other ofwhich is open to the atmosphere below the aerofoil whereby the diaphragmwill be flexed by reason of diiferences inpressure on the surfaces ofthe aerofoil, a pointer movable by the diaphra In and 00- operating witha scale for indicating the buoyancy of the machine, a scale carried bythe pointer, means for. adjusting the tension of the diaphragm, a seconddlaphragm dividing the other compartment into two phere above theaerofoil'and the other of which is 0 en to the atmosphere below the.aerofoil w ereby said second diaphragm will be flexed by reason ofdifferences in pressure .above and below the aerofoil, a pointer movableby the second diaphragm and co-opera'tingwith the scale carried by thefirst mentioned pointer for indicating the angle of incidence of theaerofoil, and means for adjusting the tension of the second diaphragm.

34. The method of determining the attitude of an. aeroplane, whichcomprises measuring the air pressure acting on the wing surfaces. J

35. The method of determining the attitude of an aeroplane to the a1rstream through which it moves, which comprises measuring the pressure ofthe air at a pluralit of points on the wing surface.

36. 'l e method of determinin the at titude of an aeroplane to the airstream through which it moves, which comprises measuring the pressure ofthe air at a plurality of points on the wing surface, one

' of said points being in proximity to the trailin edge of the-wing.

37. e method of measuring the buoychambers one of which is open to theatmoss amines .the air reactions on the wing surfaces.

38. The method of determining the angle of incidence of an aeroplane inflight whlch comprises ascertaining an avera e difi'erential pressurebetween those at t e top and bottom. cambers of an aerofoil,ascertaining a differential pressure product by the air flow on the topand bottom cambers at the trailin edge of the aerofoil, and comparingsaid differential pressures.

39. Theniethod of determinin the angle of incidence of an aero lane inlghtwhich comprises comparing t e difl'erential pressune obtainedthrough a series of openings at the top and bottom cambers of theaerofoil, said 0 enings being positioned forward of the tracilin edge ofthe aerofoil, with the dilferentia pressure obtained on said top andbottom cambers in proximity to the trailin edge.

I 40. he method of determinin the angle of incidence of an aeroplane infllght, WhlCh comprises com aring the average difi'erential pressure 0tained through a series of openings at the top and bottom cambers of theaerofoil, said 0 enin being positioned forward of the trai ing e ge ofthe aerofoil, with the differential pressure obtained on said top andbottom cambers in proximity to the trailing edge.

41. The method of indicatin the angle of incidence of an aeroplane inight, which comprises ascertaining the pressures acting normal to thetop and bottom of the wing surface at points removed from the trailingedge thereof, ascertaining the pressures normal to the air stream closeto said surfaces 1n proximity to the. trailing edge, and

BERRY RErNoLp s, a "f

